A prospective randomized clinical trial comparing a new oral sustained-release ritodrine with conventional tablets

Evaluation of maternal metabolic and cardiovascular responses to treatment with the new sustained-release oral ritodrine as compared with the conventional tablets.

Thirty-two pregnant patients who had successful intravenous tocolysis were randomly assigned to treatment with either ritodrine tablets or sustained-release capsules. After 5 days of the randomly determined first oral treatment each patient was shifted to the alternate ritodrine formulation for a further 5-day course. Each patient underwent metabolic and non-invasive hemodynamic evaluation.

Echocardiographic parameters during treatment with ritodrine tablets were not significantly different from during sustained-release capsules. Mean systolic blood pressure increased significantly during peak drug activity in patients treated with ritodrine tablets and not during treatment with the sustained-release form. Fasting plasma glucose levels were higher in patients on conventional tablets therapy than in patients on sustained-release ritodrine therapy (88.9 +/- 9 mg/dl vs. 78.7 +/- 8 mg/dl, P < 0.05) while levels following a 50-g oral glucose challenge test did not differ significantly (135 +/- 32 mg/dl vs. 124.5 +/- 27 mg/dl)

Because of fewer metabolic and cardiovascular side-effects, the new oral therapy offers some advantages over the presently available tablets.